Explanation:
Asteroid 2005 YU55 passed by the Earth yesterday, posing no danger.
The space rock,
estimated to be about 400 meters across, coasted by just inside the orbit of Earth's Moon.
Although the passing of smaller rocks near the Earth is
not very unusual -- in fact small rocks from space strike Earth daily -- a rock this large hasn't passed this close since 1976.
Were YU55 to have struck land,
it might have caused a
magnitude seven
earthquake
and left a city-sized crater.
A perhaps larger danger would have occurred were
YU55
to have struck the ocean and raised a large
tsunami.
The above radar image was taken two days ago by the
Deep Space Network
radio telescope in
Goldstone,
California,
USA.
YU55
was discovered only in 2005, indicating that other
potentially hazardous asteroids might lurk in
our Solar System currently undetected.
Objects like YU55 are hard to detect because they are so faint and
move so fast.
However, humanity's ability to scan the sky to detect, catalog, and analyze such objects has
increased notably in recent years.